Self-priming centrifugal pump



Dec. 1'4, T954 6- FABIG 2,696,789

SELF-PRIMING CENTRIFUGAL PUMP Filed Sept. 11, 1951 Fig. 2

United States Patent 'SELF-PRIMING 'CENTRIFUGAL PUMP Georg Failiig, Dusseldorf-'Gerres'heim, Germany, assign:

to Alexander 8. "Sugar, New York, N. Y.

Application September-1 1, 1951, Serial No. 246,036

1 Claim. (Cl. 103-413) The invention rela'tesrto a self-.priming centrifugal pump with avane impeller open-on 'both sides and constructed as a vanecl wheel.

With such pumps the vane impeller is enclosed in a concentric casing with annular channels provided in the casing on opposite sides of the impeller, which channels 'start'out shallow, in the proximity 'of the suction ,port at oneside casing, become gradually deeper andend shallow again in the proximity of the discharge port at the oth'er side of the casing. When the impeller is rotated, the centrifugal effect creates a ring of liquid rotating within the casing, "so that pumps constructed in this fashion can operate simultaneously as a water ring pump utilizing a displacement effect, and as a centrifugal pump, utilizing the effect of the centrifugal force. Also, it is common, with these j-pumps, to provide separate channels and separate outlet ports on the discharge side of the pump casing for the liquid delivered by the liquid ring and by the centrifugal force, while, on the other, hand, a common inlet port has been provided "on the suction side of the pump casing for the entire quantity of liquid sucked in. The pumps of this kind have the disadvantage that during the air-pumping, when the pump is primed, apart of the auxiliary liquid required for the "displacementeffect escapes through the outlet port provided for the liquid "delivered by the centrifugal effect and situated 'close to the rim of the working chamber of the pump com paratively far out on the discharge side of the pump casing. This interferes with the formation of a water ring of optimal development and perfect sealing properties, so that the suction power of the pump is diminished. This is particularly perceptible when the vane impeller runs with a larger than normal clearance within the casing. One of these pumps is shown in my Patent No. 2,282,569, dated May 12, 1942.

Some of the objects of the present invention are to provide a self-priming centrifugal pump, in which the above mentioned disadvantages are eliminated, which is simple in construction, inexpensive to manufacture, has a minimum number of parts, has particularly eflicient air-supplying capacity, quick evacuation of air, increased overall efficiency, a higher delivery head obtainable per stage, and a quick evacuation of the air from the suction line, even with considerably worn out impellers.

For a better understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. 1 is an elevational view of the inner face of the suction half of the casing.

Fig. 2 is an elevational view of the inner face of the discharge half of the casing;

lliig. 3 is a fragmentary elevational view of the impe er;

Fig. 4 is a fragmentary top view of the impeller looking upon the end of one blade;

Fig. 5 is a sectional view of one of the twisted vanes taken along the line 5-5 of Fig. 3;

Fig. 6 is a vertical sectional view of a pump embodying the instant invention shown assembled.

According to the invention there is provided another additional port on the discharge side of the pump casing, in addition to the usual outlet port 8 provided for the liquid delivered by the respective centrifugal and displacement effects. This additional port 10 is situated ahead of the said port 8 with reference to the direction of rotation of the vane impeller 10, so that through this additional port 10 auxiliary liquid can be returned the stuffing box 'packin-gs. suctionpower of the pump is-substa'ntially increased 'even "ice into the "wanting chamber of the ump frofn the dis- "charge side shortly before the air c'o'rnmences to secede sump. Accordingly with the discharge side of theipump so constructed, there will be obtained during the pumping of air, a constant and positive gre'turn flow toward the impeller 1 0 of 'that part -of :the auxiliary :liquid escaping through th'e discharge jport. Consequently, due to this circulating new of liquid, the water ri'ng required for the displacement effect is continually replenished, so that a highly effective vacuu'mmet'r-ic suction lift of the pump is obtained. As a 'result, the pump is not in the least effected by larger clearances-between impeller and the outer casing parts, not shown, or by leaks in Also for "this reason, :the

when hot and volatile liquids are "being pumped, and the priming effect '-over a high point in the suction line is guaranteed'even under the most adverse conditions and with simultaneous strong 'air-snifting. Furthermore, it is possible, without substantially decreasing the pump capacity, to give the vane impeller 10' a greater clearance in the casing to start with, with the result that the pump will not be effected by extraneous particle s,such as sand, ad'mixed in the liquid being pumped. After =the priming operation, this additional port which :has been "p'rovided become's' anadditional discharge port 10, "sotthat the discharge of the liquid delivered by the -displace- 'ment effect will have especially favorable conditions from the point of view of :process of flow.

This additional'port 10 makes it possible to :shape the discharge side "of the pump so that in comparison with the prior pum'p designs of the above patent the laterally "situated discharge channel 6-is extended :further around in the direction :of rotation of the impeller 10.

Also, in order to increase the delivery pressure'hea'd, the discharge port 10 provided in the channel as outlet ifor the 'liquiddelivered by the .centrifugal'etfect is forwardly advanced. Another feature of this invention is the remployment of impellers having spirally twisted vanes 13, the front and rear surfaces 11 and 12 of which are shaped in the form of an arc of circle or some other curve. Compared with impellers of the known types, having vanes of triangular section with flat front surfaces twisted at approximately 7 degrees relative to the impeller axis, the present vane impeller having curved front and rear surfaces and twisted to from 18 to 25 degrees and has been found to have higher efficiency so that the same energy input will yield a substantially increased capacity and delivery head. Moreover, the present impeller 10' with spirally twisted vanes runs very well balanced because there is no lateral friction due to axial thrust, and because the particular shape of the vanes is designed to give a perfect, smooth flow of the liquid.

In Fig. 1, the suction side 1 of the centrifugal pump is shaped in the usual manner and as shown in the above patent, the assembled relationship of the parts being shown in Fig. 6. The liquid is sucked in through the suction or inlet port 2 into the cells or spaces between the vanes of the impeller which is disposed between the halves or parts 1 and 5 of the casing, Fig. 1, 2, and rotating in the direction shown by the arrows 3 and 9, joining when the halves are together, as shown in Fig. 6. The sealing water ring required for the displacement effect is formed an arcuate channel 4 of varying depth on the inner face of the suction half 1. This channel 4 starts out shallow, in the proximity of the suction port 2, deepens gradually and again ends shallow at its other end. On the opposite side of the impeller and in the discharge half 5 of the casing, there is provided an arcuate channel 6 of varying depth for receiving the liquid delivered by centrifugal action and discharged through the outlet port 7. This channel 6 is also shallow on both ends, intermediately thereof having its depth nearly uniform. The liquid delivered by the displacement effect is discharged through the port 8 into annular passage 8.

According to the invention, in the casing half 5 there is provided an additional port 10, forwardly of the port 8 with reference to the direction of rotation of the impeller 10 (see Fig. 6), as indicated by arrow 9 through which, during the period of priming, shortly before the air commences to recede from the impeller cells, auxiliary liquid can return from the discharged liquid to the impeller. This returned auxiliary liquid replaces that quantity of liquid thrown out through the exterior outlet port 7 and thus lost from the sealing water ring. Therefore, due to this circulation of the auxiliary liquid, an ideal, tightly sealing liquid ring will be present at all times during the priming period. In order to obtain the desired eifect to its full extent, the additional port 10 must be located as low as possible in the discharge chamber or the casing half with which the port communicates. In multistage pumps, such as shown in the above patent, merely one additional port 10 need be provided and that will be in the pump stage adjacent to the discharge casing.

Figs. 3 to 5 there is shown the impeller vanes shaped according to the present invention. Unlike in the known self-priming pumps, the front face surface 11 and rear surface 12 of the vanes 13 are of arcuate shape or curved and the angle 14 at which the vanes 13 are twisted spirally with reference to the impeller axis, ranges from 18 degrees to 25 degrees, for instance, it is found suitable to make this angle about 22 degrees for an impeller diameter of about 130 millimeters. Thus, an impeller after twisting, has vanes of more or less crescentshaped cross-sections. These vanes are thicker on the suction edge at 17 than on the discharge edge at 18.

It will now be apparent that a substantial increase of the delivery head and of the pump capacity for the same energy input, that is, a corresponding increase in efiiciency is obtained. As shown by actual measurements, the Well designed sealing water ring of constant volume produces such values of priming time and suction lift as could heretofore be achieved with reciprocating or rotary piston pumps only. Furthermore, the present pump has as its salient feature that the production tolerances and clearances relating to the impeller and casing can be made less close which results in lower manufacturing costs and, at the same time, in an increase of the capabilities of the pump to cope with sand and similar materials.

While various changes may be made in the detailed construction, it shall be understood that such changes shall be within the spirit and scope of the present invention as defined by the appended claim.

What is claimed is:

A self-priming centrifugal pump that delivers one portion of the sucked-in liquid by displacement and another portion of the liquid by centrifugal action, comprising a vaned impeller open on both sides, said impeller having spirally twisted vanes with curved front and rear surfaces, the twist of each vane being of the order of 18 to 25 degrees with reference to the, impeller axis, the thickness from the suction edge to the discharge edge, than on the discharge edge and gradually decreasing in thickness from the suction edge of the discharge edge, a casing enclosing said vaned impeller having a common inlet port for the total quantity of sucked-in liquid in one side of the casing adjacent one side of the impeller vanes and separate channels and outlet ports for the liquid delivered by displacement and the liquid delivered by centrifugal action on the other side of the casing adiacent the side opposite the first side of the impeller vanes, said casing further having a supplemental inlet port on the discharge side of the casing adjacent to the impeller with reference to the direction of rotation and forwardly of the discharge ports through which displaced liquid is returned to the impeller from the discharge liquid, said channel in said other side of the casing provided for the liquid delivered by centrifugal action extending into the proximity of a radial plane including the discharge port for the liquid delivered by displacement, the discharge port for the liquid delivered by centrifugal action being located rearwardly of said radial plane.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,282,569 Fabig May 12, 1942 2,552,118 Sawyer May 8, 1951 FOREIGN PATENTS Number Country Date 26,689 Australia Nov. 11, 1930 621,691 Great Britain Apr. 14, 1949 715,119 Germany Dec. 15, 1941 877,322 France Sept. 1, 1942 

